Much of our work tests hypotheses concerning the influence of spatial and temporal variation in the availability of habitats or other resources on speciation and the rate of evolution of interspecific interactions. Our data are largely phylogenetic, based on variation in DNA sequences and morphological characters, and our studies vary in focus from principally ecological dimensions of resource use to emphasis on biogeographic or paleontological dimensions. Our general goal to understand the interplay of adaptation and historical contingency in ecological and taxonomic diversification, as well as the marks of evolutionary history on community structure. The context of nearly all of our studies is the interaction between insects and plants, ecological associates whose diversity and abundance make them the principal denizens of the terrestrial earth.